Disposable absorbent devices for the absorption of human exudates are widely used. These disposable devices typically have a compressed mass of absorbent formed in the desired shape, which is typically dictated by the intended consumer use. For example, in the case of menstrual tampons, the device is intended to be inserted at least partially into a body cavity for absorption of the body fluids generally discharged during a woman's menstrual period.
There exists in the human female body a complex process which maintains the vagina and physiologically related areas in a healthy state. In females between the age of menarche and menopause, the normal vagina provides an ecosystem for a variety of microorganisms, which must be maintained in a relatively delicate balance. Bacteria are the predominate type of microorganisms present in the vagina, and most women harbor about 109 bacteria per gram of vaginal secretions. The bacterial flora of the vagina is comprised of both aerobic and anaerobic bacteria. The more commonly isolated bacteria include Lactobacillus species, Corynebacteria species, Gardnerella vaginalis, Staphylococcus species, Peptococcus species, aerobic and anaerobic Streptococcal species, and Bacteroides/Preuotella species. Other microorganisms that have been isolated from the vagina on occasion include yeast (Candida albicans), protozoa (Trichomonas vaginalis), mycoplasma (Mycoplasma hominis), chlamydia (Chlamydia trachomatis), and viruses (Herpes simplex). These latter organisms are generally associated with vaginitis or sexually transmitted diseases, although they may be present in low numbers without causing symptoms.
Physiological, social and idiosyncratic factors affect the quantity and species of bacteria present in the vagina. Physiological factors include age, days of the menstrual cycle, and pregnancy. For example, vaginal flora present in the vagina throughout the menstrual cycle can include Lactobacilli, corynebacterium, ureaplasma, and mycoplasma. Social and idiosyncratic factors include presence and method of birth control, sexual practices, systemic disease (e.g., diabetes), and medication.
Bacterial proteins and metabolic products produced in the vagina can affect other microorganisms and the human host. For example, generally the pH of the vagina between menstrual periods is mildly acidic, having a pH ranging from about 3.8 to about 4.5. This pH range is generally considered the most favorable condition for the maintenance of normal flora. At that pH, the vagina normally harbors the numerous species of microorganisms in a balanced ecology, playing a beneficial role in providing protection and resistance to infection and making the vagina inhospitable to some species of bacteria such as S. aureus. The low pH is a consequence of the growth of Lactobacilli and their production of acidic products. Microorganisms in the vagina can also produce antimicrobial compounds such as hydrogen peroxide and bacteriocins which attack and eliminate other bacterial species. One example is the lactocins, bacteriocin-like products of Lactobacilli directed against other species of Lactobacilli. Some microbial products may affect the human host. For example, S. aureus can produce and excrete into its environment a variety of exoproteins including enterotoxins, toxic shock syndrome toxin-1 (“TSST-1”), and enzymes such as protease and lipase.
Vaginal menstrual toxic shock syndrome is a rare syndrome characterized by rapid onset of high fever, vomiting, diarrhea, and rash followed by a rapid drop in blood pressure and vital organ failure. TSS is associated with the presence of S. aureus bacteria and one or more exotoxins which are produced by the bacteria. The exotoxins associated with TSS include but may not be limited to Streptococcus: Exotoxin A, Exotoxin B, Exotoxin C and Staphylococca: Pyrogenic Exotoxin C, Enterotoxin A, Enterotoxin B, Enterotoxin C, Enterotoxin F, and TSST-1. Using traditional culture based techniques, S. aureus has been identified in the vagina of approximately 16% of healthy women of menstrual age (Recent clinical studies using DNA based techniques have shown this number to be much higher). It has been found that approximately 10% of the S. aureus isolated from the vagina are capable of producing TSST-1. TSS is not caused by the bacteria per se but rather by the toxic effects of the associated exotoxin which can pass from the vagina and other internal body cavities into the blood stream.
TSS has been associated with the use of absorbent pads within the vagina which may promote the growth of bacteria and the production of exotoxin in their vicinity. The syndrome has been observed with surgical dressings, and is also associated with the use of catamenial tampons. The syndrome appears to occur with elevated frequency in association with those absorbent pads which are characterized by high levels of absorbency and which accordingly are left inside the body for extended periods.
While a preferred approach for reducing the risk of TSS when using absorbent pads is proper use and frequent changes of new pads for used ones, various other approaches have been proposed by the art for reducing the risk of TSS associated with an internal absorbent pad. One approach is the incorporation of antimicrobial or bacteriocidal agents into the absorbent pad such as the use of iodine bactericides in tampons and catamenial sponges. Such an approach is not always suitable for use in the catamenial product, however, because a bactericide which is active against S. aureus can adversely affect other beneficial bacteria which make up the vaginal flora, thereby upsetting the healthy balance discussed above. Another related method describes the use of catamenial tampons comprising substances such as organic acids which will maintain a pH of about 4.5 to about 2.5 in the fluids absorbed during the use of the tampon such that the growth of pathogenic bacteria is inhibited.
Other approaches are directed to inactivation of the TSS toxin such as the administration of L-ascorbic acid for the detoxification of the S. aureus toxins, Pyrogenic, Exotoxin C (Schlievert) and Staphylococcal Enterotoxin F (Bergdoll) TSS-1. While this method does not ascribe a mechanism for the effectiveness of ascorbic acid at neutralizing TSS-1, it observes that L-ascorbic acid is known to be a reducing agent and strong antioxidant and that it may operate to inactivate bacterial toxins by reducing disulfide bonds within the toxins.
Another approach is directed to the incorporation of substances within an absorbent pad which inhibit the production of TSS exotoxins by S. aureus. This method describes the incorporation of non-toxic divalent magnesium cations in absorbent pads to reduce the concentrations of available magnesium binding ions below those critical for optimal production of TSST-1 and other staphylococcus products.
Despite these developments, there remains a desire in the art for absorbent pads suitable for internal use, including catamenial tampons, which are characterized by improved immobilization of TSST-1 toxin generated within the absorbent product without adversely affecting the normal vaginal flora.